function GVerify(options) {
  //此构造函数可能会转换为类声明 vscode里面提示这个，表示这是一个类定义
  //创建一个图形验证码对象，接收options对象为参数
  this.options = {
    //默认options参数值
    id: '', //容器Id
    canvasId: 'verifyCanvas', //canvas的ID
    width: '100', //默认canvas宽度
    height: '30', //默认canvas高度
    type: 'blend', //图形验证码默认类型blend:数字字母混合类型、number:纯数字、letter:纯字母
    code: ''
  }

  if (Object.prototype.toString.call(options) == '[object Object]') {
    //判断传入参数类型
    for (var i in options) {
      //根据传入的参数，修改默认参数值
      this.options[i] = options[i]
    }
  } else {
    this.options.id = options
  }

  this.options.numArr = '0,1,2,3,4,5,6,7,8,9'.split(',')
  this.options.letterArr = getAllLetter()

  this._init()
  this.refresh()
}

GVerify.prototype = {
  /**版本号**/
  version: '1.0.0',

  /**初始化方法**/
  _init: function () {
    var con = document.getElementById(this.options.id)
    var canvas = document.createElement('canvas')
    this.options.width = con.offsetWidth > 0 ? con.offsetWidth : '100'
    this.options.height = con.offsetHeight > 0 ? con.offsetHeight : '30'
    canvas.id = this.options.canvasId
    canvas.width = this.options.width
    canvas.height = this.options.height
    canvas.style.cursor = 'pointer'
    canvas.innerHTML = '您的浏览器版本不支持canvas'
    con.appendChild(canvas)
    var parent = this
    canvas.onclick = function () {
      parent.refresh()
    }
  },

  /**生成验证码**/
  refresh: function () {
    this.options.code = ''
    var canvas = document.getElementById(this.options.canvasId)
    if (canvas.getContext) {
      var ctx = canvas.getContext('2d')
    } else {
      return
    }

    ctx.textBaseline = 'middle'

    ctx.fillStyle = randomColor(180, 240)
    ctx.fillRect(0, 0, this.options.width, this.options.height)

    if (this.options.type == 'blend') {
      //判断验证码类型
      var txtArr = this.options.numArr.concat(this.options.letterArr)
    } else if (this.options.type == 'number') {
      txtArr = this.options.numArr
    } else {
      txtArr = this.options.letterArr
    }

    for (var i = 1; i <= 4; i++) {
      var txt = txtArr[randomNum(0, txtArr.length)]
      this.options.code += txt
      ctx.font =
        randomNum(this.options.height / 2, this.options.height) + 'px SimHei' //随机生成字体大小
      ctx.fillStyle = randomColor(50, 160) //随机生成字体颜色
      ctx.shadowOffsetX = randomNum(-3, 3)
      ctx.shadowOffsetY = randomNum(-3, 3)
      ctx.shadowBlur = randomNum(-3, 3)
      ctx.shadowColor = 'rgba(0, 0, 0, 0.3)'
      var x = (this.options.width / 5) * i
      var y = this.options.height / 2
      var deg = randomNum(-30, 30)
      /**设置旋转角度和坐标原点**/
      ctx.translate(x, y)
      ctx.rotate((deg * Math.PI) / 180)
      ctx.fillText(txt, 0, 0)
      /**恢复旋转角度和坐标原点**/
      ctx.rotate((-deg * Math.PI) / 180)
      ctx.translate(-x, -y)
    }
    /**绘制干扰线**/
    for (var j = 0; j < 4; j++) {
      ctx.strokeStyle = randomColor(40, 180)
      ctx.beginPath()
      ctx.moveTo(
        randomNum(0, this.options.width),
        randomNum(0, this.options.height)
      )
      ctx.lineTo(
        randomNum(0, this.options.width),
        randomNum(0, this.options.height)
      )
      ctx.stroke()
    }
    /**绘制干扰点**/
    for (var k = 0; k < this.options.width / 4; k++) {
      ctx.fillStyle = randomColor(0, 255)
      ctx.beginPath()
      ctx.arc(
        randomNum(0, this.options.width),
        randomNum(0, this.options.height),
        1,
        0,
        2 * Math.PI
      )
      ctx.fill()
    }
  },

  /**验证验证码**/
  validate: function (code) {
    code = code.toLowerCase() // 小写
    var v_code = this.options.code.toLowerCase()
    if (code == v_code) {
      return true
    } else {
      this.refresh()
      return false
    }
  }
}
/**生成字母数组**/
function getAllLetter() {
  var letterStr =
    'a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z'
  return letterStr.split(',')
}
/**生成一个随机数**/
function randomNum(min, max) {
  return Math.floor(Math.random() * (max - min) + min)
}
/**生成一个随机色**/
function randomColor(min, max) {
  var r = randomNum(min, max)
  var g = randomNum(min, max)
  var b = randomNum(min, max)
  return 'rgb(' + r + ',' + g + ',' + b + ')'
}
export { GVerify }
